Herbert Spencer Jackson was born in New York state in 1883 and received his college education from Cornell, Harvard, and Wisconsin universities. He held posts at the universities of Delaware and Oregon and was chief in botany at the Purdue Agricultural Experiment Station for thirteen years before going to Toronto University in 1929 as professor of mycology in the Department of Botany, of which he was the head from 1941 on. He had long been deeply interested in problems associated withe the origin, development, and classification of fungi. Before going to Toronto University he was recognized as a world authority on the rust and smut fungi, and contributed approximately thirty-one journal articles on these topics.

In the Toronto area Professor Jackson found few rust species. Consequently, he gradually shifted his emphasis to the Thelephoraceae, a neglected group of great basic significance, and important as well in the carbon cycle as wood-destroying fungi. To a better understanding of this group, he and his students contributed some sixteen articles. Dr. Jackson was largely instrumental in building up the fungus herbarium in his department, which numbered some 94,000 accessions and included an unusually complete collection of the fungi occurring in a unique region, the Temagami Forest Reserve.

Iris and his stamp collection were his hobbies, and in connection with the former, during his last year, he built himself a fitting memorial by bringing together at the Glendon Hall Botanic Garden in Toronto a collection of nearly 500 of the newer iris varieties of distinction, to found the finest collection of its sort in Canada.